Recently bought my 97 1500 5.9l with 60k miles, engine light came on Friday while driving home from work, P0302 (misfire in #2)..(I'm getting to #8 here soon). It also idled bad and shuddered when I'd take my foot off of the brake when in gear. I tested spark..all good. Didn't check fuel cause I don't know how. After some reading I decided to replace the IAC sensor, throttle position sensor, cleaned the throttle body, and replaced the wires and plugs. Runs great now, code went a way!

But, I pulled the #8 plug and noticed oil residue on the plug. What does this mean? Bad head gasket or something?



All of the other plugs looked similar to this, not sure if this is ok or bad:



Plug #5 was hard to remove because of some junk/material around the plug itself. Had to chisel it out with a screw driver. What would cause this this? #5 is directly below the oil fill hole in the valve cover gasket...maybe some oil dripped down in there and hardened over time??? Anything to be concerned with? Once I could get my socket around the spark plug it came out just fine.


Let me know your thoughts! Thanks!

 

Plenum gasket.

 

Truck has obviously sat most of its life being only 2,700 miles a year.
-put the OEM IAC back on but clean it carefully as most who replace it have troubles later
-when you had the throttle body off did you look in the plenum for oil? It's not super common but can be leaking.
-when sitting a lot or driven very few miles not getting warmed up a lot an engine can easily foul plugs. Get it hot and drive it long and hard.
-if the plenum has no puddles of oil, run Seafoam and replace plugs one more time.
-also shouldn't need to replace the TPS either so hang on to the original

 

I'll see if I can dig the IAC and TPS out of the trash :-) and I've been driving it frequently.
Here are some pics inside the plenum. Best I could get since I couldn't get a light inside. I didn't see any puddling but it definitely has a "coating" of oil inside. Would this suggest the classic plenum gasket issue, or perhaps just a bad PCV valve or something?

 

That looks absolutely normal. The PCV will let oil and oil vapor into the plenum (thank you emissions control commies) so it will always look wet and a little brown. I wouldn't worry about it. Mine always looks like that. If you throw a new PCV on, only get the MOPAR one from the dealer. They are small but integral parts and aftermarket ones are not as good (just like the sensors). Keep driving it and getting it good and hot. Use Techron, Lucas, and Seafoam religiously. Happy driving! I just turned 260,000 on mine!

 

Wow, 260k! Congrats! When you say Lucas, what products are you talking about? Seafoam religiously like at every oil change? I'm new to these trucks/Dodge. What other things should I pay attention to beyond normal maintenance?

 

Every oil change is a good regimen but maybe overkill. I use Techron or Lucas injector cleaner every month or so. Then twice a year, I run a Seafoam treatment through the booster. You can do half the can in the booster and half in the tank. I've been fighting carbon and ping ever since I bought it in 2001 so that's what works for me.

 

There is an old Technical Service Bulletin... TSB 18-48-98 that addresses issues with spark plug misfires, particularly #8 in my case. Although, probably not the root of your problem...it's worth checking out.as a possible contributing factor.
http://dodgeram.info/tsb/1998/18-48-98/18-48-98.htm

 

Thanks for sending. I'll look at my wiring and make any corrections.